Structured illumination (SI) or patterned illumination projects a narrow band of light onto a three-dimensional scene to produce lines of illumination that appear distorted. The distortions can be imaged and used to reconstruct the surface shape of one or more objects within the scene, by triangulation of the position of the distorted lines.
Patterns of parallel stripes are widely used in structured illumination. Two common methods for stripe pattern generation are laser interference and projection. The laser interference method uses two laser beams which interfere to generate regular line patterns. Different pattern sizes can be obtained by changing the angle between these beams. This method generates fine patterns with unlimited depth of field. However, the laser interference technique has disadvantages including high cost associated with implementation, incapability of modulating individual stripes, and possible interference with beams reflected from objects.
The projection method, on the other hand, uses a projector with an incoherent light source for generating patterned light (e.g. a video projector). Patterns may be generated by a display within the projector, such as a liquid crystal (LCD) display.
There still remains a need for developing systems and methods for capturing three-dimensional images with high resolution and low cost. Furthermore, there is a need for a robust method to detect the projected lines over a wide depth of field (DOF).